1. Field of the Invention
The present disclosure relates to a dry bonding system and a wearable device for skin bonding including the same.
2. Discussion of Related Art
Wearable devices are technology for clothing and accessories incorporating a computer and existing electronic technologies. Since the wearable device often interacts with a human body while in contact with the human body, various fields of sciences have been developed on an interface between the wearable device and the human body. According to this trend, there have been increasing demands and researches on a diagnosis wearable device that merges with a diagnosis device based on the virtue of a dry bonding technology. For example, there have been ongoing researches about application of the dry bonding technology in order to improve the stability and permeability that do not meet requirement for manufacturing a patch type sensor that measures a biometric signal, such as electrocardiogram and pulse, or manufacturing a cosmetic patch for beauty care, and further in order to amplify a biometric signal.
In nature, various mechanisms of bonding methods are present, for example, slime of a snail, protein of a hard-shelled mussel, insect wing joining, legs of a gecko lizard, legs a jumping spider, and seeds of thistle. Since the bonding systems in nature are significantly superior in the efficiency, various adhesives, such as an adhesive band for medical treatment, an adhesive tape, post-it and Velcro, are made to mimic the bonding systems in nature. However, in order to combine a ultra-sensitive patch type sensor to an object, the bonding method needs to satisfy the following requirements. First, a boning portion does not generate a great disturbance (noise) in a signal transmission process. Second, a sufficient adhesion force is ensured regardless of a curvature or roughness of a surface of the object to prevent the patch from being easily separated. In addition, attaching and detaching processes are easy, and the adhesion force is maintained in the mid of the processes. Finally, a surface of a measurement object is not damaged, and especially, in the case of the bonding method used for human skin, stimulus, contamination, or unpleasant sensation does not occur.
Therefore, a wet bonding method has constraints in the use since detachment requires a great force or leaves some scars or skin troubles, and adhesion force is lowered in a repeated use. In this context, a bio-inspired dry bonding system is considered as a dry adhesive capable of achieving repeated attachment/detachment without leaving contamination and damage on a surface of an object based on interaction of fine ciliary, and thus studied in various fields. However, the bio-inspired bonding system has an adhesion force which does not reach a predetermined level corresponding to the existing medical wet tape. In addition, as for a wearable sensor for skin bonding, various technical concepts have been reported, but there is need of studies on the permeability and bonding issues at an interface between a device and a skin.
To take the ultra-sensitive sensor for skin bonding and the dry medical adhesive for optimizing biometric signal detection as a representative example of the above study, first, there is an overseas research (Nature Communication 4:1702), conducted by Yang Seung-Yun's research team in a Harvard medical school based on bio-mimicking the shape of a micro needle of a cactus. However, this method has insufficient adhesion force and limitation in application of an ultrasensitive sensor.
In the second example, Karp's research team in Harvard Medical school has studied a skin patch which is attached to a medical device, a study on a medical tape with regard to easy separation of a patch and prevention of skin damage by using bio-mimicking a spider web system. However, this method shows a lower adhesion force compared to the existing adhesive, and related researches are only focused on the separation of a patch.
The third method involves a reversible electric connector using interlocking of fine ciliary, a multifunctional sensor using the same, and a method of manufacturing a sensor having multiple functions using the same (Korean Unexamined Patent Application Publication No. 10-2011-0050382) which suggests a reversible electric connector that can maximize the efficiency of electricity by connecting electrodes using a bio-inspired nanoscale structure to minimize generation of resistance and also suggests a multifunctional sensor having the nanoscale structure that can respond to a small pressure and small force in a delicate manner and provide a great sensitivity reacting to a small change. However, when two nanostructure surfaces are bonded to implement nanoscale interlocking, the bonding lacks an adhesive function that is required for application of a diagnosis wearable device.
The fourth method, referred to as Epidermal Electronics, developed by University of Illinois at Urbana-Champaign, involves a wearable sensor for skin bonding in which a pattern is attached to a skin using a LAP ON A CHIP or a patch type sensor system, which is thin and bendable unlike an existing wafer based chip, through a tattoo scheme. However, this technology is complicated in the manufacturing and the structure so that practical use is limited. In addition, the use of the tattoo bonding system may cause reluctance to skin bonding and weakness in the permeability and stability.
Finally, there is a research by a School Shanghai Jiao Tong University research team, conducted on a medical skin patch that is configured to measure electrocardiogram (ECG) by merging a dry bonding skin patch with a dry electrode based on a mushroom shape biomimicking. However, this method shows a weak bonding structure against a shear stress, and thus not sufficient for being applied to a skin patch.
To summarize, various researches and developments are present about the ultrasensitive sensor technology and the dry bonding system, but still have limitation on the technical performance, and leaves much to be done in merging the ultrasensitive sensor technology and the dry bonding system to manufacture a diagnosis wearable device.